An eating disorder is more than just a troubled relationship with food. It is an illness that can leave devastation in its wake. And with an estimated 20 million women and 10 million men suffering from an eating disorder at some point in their life, it’s a good bet that you know someone dealing with one — perhaps yourself.

Overcoming an eating disorder or keeping one from taking hold means getting educated about what it means. In recognition of National Eating Disorders Awareness Week, here are five facts everyone should know.

1. The definitions are evolving.

As research adds up, our understanding of eating disorders is changing. The latest version of the Diagnostic and Statistical Manual of Mental Disorders, called the DSM-5, now breaks it down this way:

Binge-eating disorder: This earned its own category after it was realized that binge eating — meaning eating much more than intended in a short time —is more common than once realized. How do you know you are a binge eater and not just an overeater? You feel out of control, you react to your eating with guilt, disgust, shame or embarrassment, and you binge at least once a week over the course of three months, often in secret.

Anorexia nervosa: Those with this illness are no longer said to refuse food, which implies a choice. Instead, the new definition recognizes that a pathological fear of becoming fat combined with a distorted body image leads to drastic attempts to stay thin at all costs, including calorie restriction and excessive exercise.

Bulimia nervosa: When binge eating is followed by efforts to avoid weight gain, such as through self-induced vomiting or use of laxatives, it becomes bulimia nervosa. It was once thought at least two episodes of bingeing and purging weekly were necessary to qualify as bulimia, but the new definition lowers that to once a week.

2. Eating disorders are not a lifestyle choice.

From the outside, some eating disorders can look like vanity gone amuck. But more than a desire to emulate supermodels is at work. A combination of genetic, psychological, biological, behavioral and social factors are now known to play a role.

Recent studies reveal, for example, that a gene variation may lead to binge eating in teens; that brain activity is different in those with anorexia; and that having an apple body shape increases susceptibility to binge eating, as does a tendency toward impulsivity.

Added to all this is a potent emotional fuel: a comparison culture that can send body dissatisfaction soaring.

3. Eating disorders often go hand-in-hand with other problems.

If you have an eating disorder, your chance of co-occurring conditions skyrockets. You are more likely to have a mood disorder such as depression or bipolar disorder, for example, and you are at elevated risk of obsessive-compulsive disorder, research shows. Not only that, alcohol and drug use disorders occur at four times the rate in those with eating disorders than in the general population.

These statistics are troubling because each issue complicates the other. That’s why treatment that focuses on the whole person, not just on the eating disorder in isolation, is crucial for healing.

4. They can kill.

If you have ever doubted that eating disorders are serious stuff, consider this: anorexia nervosa has the highest death rate of any mental disorder. Some struggling with it die of starvation; others die from suicide. Anorexia can also cause brain damage, organ failure and destroy bones, among just a few of its effects.

With bulimia, the binging and purging that so commonly defines it can cause an electrolyte imbalance that makes heart attack, stroke or death a real possibility. Stomach acids can also destroy tooth enamel.

Binge eating often results in obesity, which has been linked to a whole range of health problems, including cardiovascular disease and cancer.

In sum, there’s plenty to fear from eating disorders, and they shouldn’t be made light of or ignored.

4. Recovery is possible.

If you’re dealing with an eating disorder or are trying to help someone who is, you know it can leave you feeling hopeless, out of control and terrified. But a variety of treatments are available, and the possibility of full recovery is real. Among just a few of the options are medications that can help stabilize mood and address any co-occurring disorders, and psychotherapy, which can teach the sufferer how to identify and change their distorted beliefs.

No matter the type of eating issue, the best treatments are those that recognize that each person’s experience of an eating disorder is unique and their path to healing should be as well.

If you struggle with food and body image but aren’t sure if your issues reach the level of an eating disorder, the National Eating Disorders Association offers an online screening quiz that can help you figure out if it’s time to seek help. It doesn’t replace a diagnosis from a professional, but it can give you a sense of where you stand and where you should be headed.